Surface Heating System for Tubing or Piping

ABSTRACT

A system and method allowing for the transfer of heat from a heating element in a tube heating system to production tubing in downhole pipes. The heating tube is comprised of double walled and double threaded pipe. The transferred heat warms the material being extracted from a subterranean formation and collected at the surface. Warming the material prevents the build-up of paraffins, asphaltenes, or other materials that may potentially clog production pipe in downhole applications.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to systems and methods for producing, delivering, or transferring heat to the tubing or piping of producing or non-producing oil, gas, or water wells with the purpose of improving production therefrom.

Background of the Invention

One of the many problems in oil and gas production is maintaining adequate production flow. Blockages, decreased flow, and total obstruction can occur in any well including wells that once had high flow. Wells may become obstructed by paraffin and asphaltene deposits that attach to the inside of the tubing. Additionally, the oil itself can sometimes have such a high viscosity that flow decreases even under naturally ambient temperatures.

Asphaltenes and paraffins are commonly occurring components of crude oil. Asphaltenes and paraffins have the potential to interfere with production and in some instances can cause a complete shutdown. Asphaltenes are large polyaromatic agglomerates composed primarily of heterocyclic rings. Asphaltenes are believed to be held in solution in crude oil by naturally occurring petroleum resins that adhere to the outer surface of the asphaltene agglomerate.

During production, asphaltenes may destabilize and precipitate because of temperature changes, pressure, and/or the chemical composition of the crude oil. Paraffins are saturated hydrocarbon waxes that may precipitate and deposit in areas where the system's temperature falls below the solubility temperature of the paraffins; this is known as Wax Appearance Temperature (WAT). Paraffins are similar to asphaltenes in that they too, can potentially interfere with or completely stop production.

Consequently, there is a need for improved heating systems for tubing and piping in the production of oil, gas, and water wells. Further needs include improved methods for oil, gas, and water production using the aforementioned surface heating system.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

These and other needs in the art are addressed in one embodiment by a surface heating system disposed around production pipe. The system includes a heating tube. The heating tube includes an exterior tubing section. The heating tube further includes an interior tubing section. The heating tube still further includes a baffle. These and other needs in the art are addressed in another embodiment by a surface heating system disposed around production pipe. The system includes a heating tube. The heating tube is segmented into jackets. The heating tube includes an exterior tubing section. The heating tube further includes an interior tubing section. The heating tube still further includes a baffle. These and other needs in the art are addressed in another embodiment by a method of transferring heat to production tubing. The transferring of heat to production tubing includes pumping a heating element downhole through double walled tubing. The transferring of heat to production tubing includes warming the production tubing with the heating element. The transferring of heat to production tubing also includes pumping the heating element back to the surface. The transferring of heat to production tubing also includes taking (i.e., removing) the heating element out of the double walled tubing. The transferring of heat to production tubing further includes providing (i.e., moving) the heating element to a heater. The transferring of heat to production tubing further includes the heating or reheating of the heating element. The transferring of heat to production tubing further includes moving the heating element to a pump. The transferring of heat to production tubing still further includes pumping the heating element back into the double walled tubing for recirculation. The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims.

DETAILED DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:

FIG. 1 illustrates an embodiment of exterior and interior views of the double-threaded, double-walled surface heating system;

FIG. 2 illustrates an embodiment of a horizontal cross section of the surface heating system;

FIG. 3(a) illustrates an embodiment of a vertical cross section of the uppermost piece of the surface heating system;

FIG. 3(b) illustrates an embodiment of a representation of the vertical cross section of an empty uppermost piece of the surface heating system;

FIG. 4(a) illustrates an embodiment of a vertical cross section of the bottommost piece of the surface heating system;

FIG. 4(b) illustrates an embodiment of a representation of the vertical cross section of an empty bottommost piece of the surface heating system;

FIG. 5 illustrates an embodiment of a vertical cross section of two jacket segments connected by hoses;

FIG. 6 illustrates an embodiment of a jacket segment capable of being connected by hoses to other jacket segments;

FIG. 7 illustrates an embodiment of a vertical cross section of the connection piece of the surface heating system; and

FIG. 8 illustrates an embodiment of a vertical cross section of the middle piece of the surface heating system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In an embodiment, as shown in FIG. 1, a surface heating system 5 may address the problem of asphaltene and paraffin deposits in oil, gas, and water wells; where the cool zone temperatures serve as a catalyst that causes paraffin and asphaltene to solidify in the tubing and decrease or halt production. Hereafter, for the sole purpose of brevity, wells will be referred to as “oil wells,” however, it is to be understood that the applications apply equally well to gas or water wells. Heating systems for oil wells and components thereof are known in the industry. However, the existing technologies may Jack efficacy or long-term reliability. Further, without limitation, surface heating system 5 eliminates these problems by directly heating the tubing where the asphaltenes and paraffin solidify and attach.

FIG. 1 illustrates an embodiment of surface heating system 5. Surface heating system 5 provides heat to downhole pipe, not illustrated, to facilitate the transportation of product from an underground formation to the surface. Heat is provided by a heating element 7 which may comprise, but is not limited to, light heat transfer oil, hot water, steam, or any combinations thereof. It is to be understood that reference 7 for the heating element is for illustration purposes to show the fluid direction of heating element 7. As illustrated in FIG. 1, heating of downhole pipe facilitates movement of product 8 through interior of production tubing 20 from an underground formation to the surface. It is to be further understood that product 8 may comprise, but is not limited to, oil, gas, and or water. Heating product 8 as it moves through interior of production tubing 20 prevents the build-up of paraffins, asphaltenes, or other materials that may potentially clog downhole pipe. In an embodiment, surface heating system is disposed downhole. In embodiments, surface heating system 5 is put into place as the original oil well tubing system. In other embodiments, surface heating system 5 is used to replace removed oil well tubing from oil wells. In both embodiments, surface heating system 5 is placed downhole where surface heating system 5 may be used to circulate and recirculate heat to the interior of production tubing 20 of surface heating system 5. Heating element 7 may be heated or reheated (i.e., at the surface) by any suitable heating methods. Heating element 7 may be heated to any desired temperature that is suitable to provide heat to product 8. In embodiments, heating element 7 is heated to a temperature between about 200° F. and about 800° F.

As shown in FIGS. 1 and 2, an embodiment of surface heating system 5 may comprise an exterior tubing section 10, an interior tubing section 15, and an interior baffle 35. Interior tubing section 15 may be made of any material that is thermally conductive and capable of withstanding the high temperature of the heating element 7 contained within surface heating system 5. In an embodiment, the material may need to withstand temperatures of about 200° F. to about 800° F. Interior tubing section 15 may be made of, but is not limited to, carbon steel, nickel, copper, titanium, chromium, molybdenum, or any combination thereof. The diameter of interior tubing section 15 may be of any size suitable to mate with the downhole piping being used for a particular application. Interior tubing section 15 serves many functions. An example of these functions is the transportation of oil or other material through interior of production tubing 20 from an underground formation to the surface. Interior tubing section 15 also allows for the flow of heat to move through interior tubing section 15 from heating element 7 to oil or other materials being transported to the surface from an underground formation. As illustrated in FIG. 2, another function of interior tubing section 15 is to serve as the base for which baffle 35 supports exterior tubing section 10.

Exterior tubing section 10 is formed around interior tubing section 15 and is of a larger diameter than the diameter of interior tubing section 15. Exterior tubing section 10 may be made of any material that is thermally conductive and capable of withstanding the high temperature of heating element 7 contained within surface heating system 5. The material may need to withstand temperatures of about 200° F. to about 800° F. Exterior tubing section 10 may also be made of, but is not limited to, carbon steel, nickel, copper, titanium, chromium, molybdenum, or any combination thereof. As illustrated in FIGS. 1 and 2, the interior tubing section 15 and exterior tubing section 10 form containment area 16. Containment area 16 is divided into two separate containment areas 16 by two baffles 35. The two containment areas 16 hold heat element 7 within a defined area. Containment area 16 is defined by the diameter of the interior tubing section 15 and exterior tubing section 10 and the relative distance between the two sections 10 and 15. Containment area 16 may be of any volume desired. In some applications, the volume may be larger to transport a greater volume of heating element 7 downhole to provide more heat to interior of production tubing 20. A smaller volume may be used for applications desiring less heat from heating element 7.

As shown in FIG. 2, baffle 35 is used to separate and support interior tubing section 15 and exterior tubing section 10. As with exterior tubing section 10 and interior tubing section 15, baffle 35 may be made of any material that is thermally conductive and capable of withstanding the high temperature of heating element 7 contained within surface heating system 5. The material may need to withstand temperatures of about 200° F. to about 800° F. Baffle 35 may be made of, but is not limited to, carbon steel, nickel, copper, titanium chromium, molybdenum, or any combination thereof. Baffle 35 may serve as a support structure for exterior tubing section 10 but may also provide other functions. In an example of another function as illustrated in FIG. 2, baffle 35 separates heating element 7 into two containment areas 16. In one containment area 16, heating element 7 is pumped downhole. In the opposing containment area 16, heating element 7 is pumped back up to the surface for recirculation and reheating. Movement of heating element 7 through the containment areas 16 provides heat to interior 20 substantially the entire length of the downhole tube.

In an embodiment, surface heating system 5 is placed in-line with downhole pipe 6 as the pipe is placed downhole into a formation. As seen in FIGS. 3(a) and 3(b), surface heating system 5 is comprised of individual sections. Individual sections of surface heating system 5 may be of any length suitable for downhole operations and allowable on a platform such as an oil derrick. Sections may range from five feet to thirty-five feet or longer. Surface heating system 5 is comprised of a bottom section 60, middle section 110, and top section 90. Middle section 110 may comprise a single or multiple sections.

As shown in FIGS. 4(a) and 4(b), bottom section 60 is comprised of, but is not limited to, an exterior tubing section 10, an interior tubing section 15, and an interior baffle 35. Without limitation, exterior tubing section 10, interior tubing section 15, and baffle 35 allow bottom section 60 to perform many different functions. An example of these functions is illustrated in FIGS. 4(a) and 4(b). Baffles 35 in bottom section 60 have transfer holes 50. Transfer holes 50 may range from any size or shape and can range from one transfer hole 50 to a plurality of transfer holes 50. Transfer holes 50 allow for heating element 7 to cross between two containment areas 16 of surface heating system 5. This allows for heating element 7 to move from containment areas 16 in which heating element 7 is being pumped downhole to containment areas 16 in which heating element 7 is being pumped to the surface for recirculation and reheating. In FIGS. 4(a) and 4(b), containment areas 16 are limited in the depth as they traverse through bottom section 60. Buffer zone 61 separates containment areas 16 and outside threading 80. Buffer zone 61 may be comprised of solid metal which may allow for structural stability. As illustrated in FIGS. 4(a) and 4(b), another function of bottom section 60 is to mate with downhole pipe that is not part of surface heating system 5. Outside threading 80 is used to mate with other types of downhole pipe. On the opposing end of bottom section 60, both the exterior tubing section 10 and interior tubing section 15 are threaded with inside threading 81 to mate with other sections of surface heating system 5.

In embodiments as shown in FIGS. 3(a) and 3(b), bottom section 60 (not illustrated) may mate directly to top section 90. In other embodiments (not illustrated), bottom section 60 may mate with a middle section 110. Middle section 110, as illustrated in FIG. 8, in an embodiment may comprise a majority of surface heating system 5. Middle section 110 may be comprised of, but is not limited to, an exterior tubing section 10, an interior tubing section 15, and an interior baffle 35. Interior baffle 35 is represented in FIG. 8 by dashed lines for illustrative purposes because interior baffle 35 is removed for the cross-sectional view shown. A cross section of middle section 110 is illustrated in FIG. 8. One end of the double threaded and double tubed middle section 110 has outside threading 80 while the opposite end has inside threading 81. This allows for middle section 110 to be attached to a multitude of sequential middle sections 110, bottom section 60, and/or top section 90. Containment areas 16 in middle section 110 are separated by baffles 35 that oppose each other. Containment areas 16 allow for the movement of heating element 7 from one section to the next. In other embodiments, bottom section 60 may attach directly to top section 90.

Top section 90, as illustrated in FIG. 3(a), of surface heating system 5 may be exposed at or near the surface. Top section 90 may be comprised of, but is not limited to, an exterior tubing section 10, an interior tubing section 15, and an interior baffle 35, not shown but represented by dotted lines. Similar to bottom section 60, containment areas 16 are limited in depth as they traverse through top section 90. Buffer zone 61 separates containment areas 16 and inside threading 81. Buffer zone 61 may be composed of any suitable material which may allow for structural stability. In an embodiment, buffer zone 61 comprises solid metal, for instance stainless steel. An example of the functions of top section 90 is illustrated in FIGS. 3(a) and 3(b). The function of inside threading 81 allows for other types of downhole pipes to attach to top section 90. On the opposing side of top section 90, the interior tubing section 15 and exterior tubing section 10 have outside threading 80. This allows for top section 90 to connect with middle sections 110 of surface heating system 5. Baffles 35, unlike in bottom section 60, do not have transfer holes 50. One containment area 16 allows for the heating element 7 to travel downhole, and opposing containment area 16 allows for the heating element to travel back up to the surface. A further example of a function performed by top section 90 is that it provides both the entrance and exit of heating element 7 from the heating and pumping station to the surface heating system 5. Inlet 40 and outlet 45 allow for heating element 7 to both enter and exit the surface heating system 5. Both inlet 40 and outlet 45 may be positioned, as illustrated in FIGS. 3(a) and 3(b), on the sides of top section 90. In this 15 embodiment, they penetrate through exterior tubing section 10. The penetrations are not limited to an exact spot on exterior tubing section 10 and may also be positioned on top of or on the sides of buffer zone 61. Inlet 40 and outlet 45 are comprised of connections that allow for heating element 7 to move from surface heating system 5 to the heating station and pump. Attachment may be any suitable attachment means, without limitation, attachment means include hose connections, thread attachments, or permanently attached hoses. Heating element 7 is heated in a furnace heater using gas or electricity and then pumped downhole through inlet 40. Heating element 7 passes through top section 90, middle sections 110, and bottom section 60. After passing through transfer holes 50 in bottom section 60, heating element 7 returns to the surface along the same path in the opposite direction and out through outlet 45 back to the heating or pump to be recycled and sent back downhole through inlet 40.

In some embodiments, bottom section 60, middle sections 110, and top section 90 each have a least one connection section 100 that is used to connect surface heating system 5 sections together. Connection section 100 may be of any suitable length. In some embodiments, connection section 100 is not used to connect surface heating system 5 to any other types of downhole pipe except other surface heating system 5 sections. As illustrated in FIG. 7, the connection between sections of surface heating system 5 involves three distinct threaded rings of pipe. Production tubing 20 forms the inner most pipe, downflow ring 101 is the next layer of pipe, and upflow ring 102 forms the outermost layer of pipe. Downflow ring 101 forms a containment zone 201 in which heating element 7 flowing downhole may travel.

The containment zone 201 is defined by its inner most wall 202, which is the shared outer most wall 203 of production tubing 20, and its outer most wall 204, which is the shared inner most wall 205 of upflow ring 102. This defined containment zone 201 allows for a heating element 7 to transfer between one section of surface heating system 5 to another. As illustrated in FIG. 7, downflow ring 101 deforms from a ring that surrounds production pipe 20 by twisting along the length of connection section 100 to connect to baffle 35, not shown but illustrated by dotted lines, and containment zone 16. Likewise, upflow ring 102 deforms around downflow ring 101 deformation to connect to the opposing baffle 35, not illustrated, and opposing containment zone 16. Containment zones 16 are defined, as stated above, by baffles 35, interior tubing section 15, and outer tubing section 10. Containment zones 16 traverse down the length of a section of surface heating system 5 before deforming back into connection section 100 at the opposite end of the pipe. One end of a section of surface heating system 5 may have outside threads 80 while the opposing sides will have inside threading 81. Without limitation, this will allow for sections of surface heating system 5 to form a water tight seal.

When forming a water tight seal between sections, (e.g. bottom section 60 and top section 90, bottom section 60 and middle section 110, middle section 110 with another middle section 110, middle section 110 and top section 90) an issue may arise with the over-torqueing of the sections at connection sections 100. This may damage outer threading 80 and inner threading 81. Over-torqueing may also damage production pipe 20, downflow ring 101, and upflow ring 102. Damage to rings 101 and 102 may cause heating element 7 to move between containment zones 16, which may allow for the ineffective heating of production tubing 20. As illustrated in FIG. 7, in order to prevent over-torqueing along two connection sections 100, a crush gasket 103 is placed between two sections of production tubing 20. Crush gasket 103 may be comprised of any material suitable for a crush gasket. In embodiments, crush gasket 103 may comprise, stainless steel, carbon steel, copper, aluminum, brass, neoprene, plaster, nylon, felt, or any combination thereof. Placed along the ridge of the threaded ring of production tubing 20, crush gasket 103 may prevent the accidental or intentional over-torqueing when forming a water tight seal between connection sections 100.

Surface heating system 5 may comprise, but is not limited to, a bottom section 60 and top section 90. In other embodiments, bottom section 60 may attach to a single or multiple middle sections 110 before attaching to top section 90. Still further embodiments allow for the downhole pipe to comprise, but is not limited to, a bottom section 60, multiple middle sections 110, and a top section 90 at multiple isolated areas along the downhole pipe. Each individual area along the downhole pipe may connect to other individual areas along the downhole pipe 35 by a hose 65. This allows for applications that may desire only specific areas of the downhole pipe to be heated by surface heating system 5. Without limitation, this may reduce the amount of heating element used, pumping pressure, energy, and time while allowing for all desired areas of the downhole pipe to be heated.

In still other embodiments, segments of surface heating system 5 are disposed around production tubing 20, as illustrated in FIG. 5. Additionally, segmented jackets 115 may be placed strategically either during the initial tubing placement or subsequently after tubing placement has already occurred. Placing segmented jackets 115 after tubing has already been placed includes removing production tubing 20 from its downhole position and surface heating system 5 to be installed around production tubing 20, before the subsequent re-installment of production tubing 20. Jackets 115 can be positioned over sections of downhole pipe that have or are likely to encounter temperatures low enough to create asphaltene or paraffin blockages or obstructions. In this embodiment, surface heating system 5 may not transport production material to the surface. Instead, as illustrated in FIG. 5, surface heating system 5 comprises a single or multiple segmented jackets 115.

As illustrated in FIG. 6, each jacket 115 may comprise, but is not limited to, an exterior tubing section 10, interior tubing section 15, and walls 36. Walls 36 may provide the same function as baffles 35 and are comprised of similar material. As in the earlier mentioned embodiments, there are two distinct containment areas 16, not shown. One containment area 16 for sending heating element 7 downhole and the other for returning heating element 7 to the surface. Containment areas 16 are in the shape of a crescent. Containment areas 16 are defined by exterior tubing section 10, interior tubing section 15, and walls 36. The diameter of the crescent may be of any size that allows jacket 115 to fit around the downhole pipe. As illustrated in FIG. 5, both segments of jacket 115 attach to each other around production tubing 20. Attachment means may include, but are not limited to, screws, nuts and bolts, cutouts, adhesive, buckle, or ally combination thereof. Selecting the appropriate diameter and connection method allows for the segments of jacket 115 to attach to the pipe. In order to prevent the slipping of jacket 115 along production tubing 20, interior tubing section 15 may have gripping material. Gripping material may include, but is not limited to, adhesive material, checkering, texturing, or any combination thereof to prevent slipping of the jacket when attached to production tubing 20. With no threaded ends, each containment area 16, of segmented jack 115, has an inlet 40 and an outlet 45. As illustrated in FIG. 5, inlet 40 and outlet 45 are positioned opposite each other on the ends of a segment. Inlet 40 and outlet 45 each have a hose connection 67 for a hose 65. Hose 65 attaches to outlet 45 of one containment area 16 of an individual segment to inlet 40 of another segment further downhole by hose connection 65, as illustrated in FIG. 5.

In order for heating element 7 to be pumped downhole and then pumped back to the surface, hose 65 is attached between outlet 45 and inlet 40 of two containment areas 16 housed in one segmented jacket. Hose 65 may range in size from, but is not limited to, 0.25″, 0.5″, 0.75″, 1.00″, 1.25″, 1.5″, 1.75″, or 2″ inch diameter coupling tubing. The length of hose 65 may be of any length needed to connect one containment area to another, as seen in FIG. 5. Hose connections 66 and 67, as illustrated in FIG. 5, connect hose 65 to inlet 40 and outlet 45. Hose 65 may be made of any material that may withstand contact with any other materials naturally occurring or otherwise that may come into contact with hose 65. Hose 65 may be made of, but is not limited to, stainless steel, titanium, copper, carbon steel, or any combination thereof. In other embodiments, hose 65 may be protected from contact with production tubing 20 or other materials by a protective coating that surrounds hose 65. The productive coating may comprise, but is not limited to, a plastic, metal, cloth, chemical compound, or any combination thereof.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims. 

What is claimed is:
 1. A heating tube, comprising: an exterior tubing section; an interior tubing section; and a baffle.
 2. The heating tube of claim 1, wherein the exterior tubing section is threaded at both ends.
 3. The heating tube of claim 1, wherein the exterior tubing section has an inlet and an outlet.
 4. The heating tube of claim 1, wherein the interior tubing section is threaded at both ends.
 5. The heating tube of claim 1, wherein the interior tubing section allows material from a subterranean formation to flow through the interior tubing section to a surface.
 6. The heating tube of claim 1, wherein the baffle supports and separates the exterior tubing section from the interior tubing section.
 7. The heating tube of claim 1, wherein the baffle separates movement of a heating element from traveling downhole and traveling to the surface.
 8. The tube heating system of claim 1, wherein the baffle comprises transfer holes.
 9. A heating tube, comprising: a segmented jacket; an exterior tubing section; an interior tubing section; and a baffle.
 10. The heating tube of claim 9, wherein the segmented jacket comprises two segments.
 11. The heating tube of claim 10, wherein the segments comprise an inlet and an outlet.
 12. The heating tube of claim 10, wherein the segments attach to each other.
 13. The heating tube of claim 10, wherein the segments are connected by a hose.
 14. The heating tube of claim 9, wherein the interior tubing section comprises surface texture.
 15. A method of transferring heat to a production tube, comprising: pumping a heating element downhole through a double walled tube; warming the production tube with the heating element; pumping the heating element back to the surface; removing the heating element out of the double walled tubing; providing the heating element to a heater; heating the heating element; moving the heating element to a pump; and pumping the heating element back into the double walled tubing downhole pipe for recirculation.
 16. The method of claim 15, wherein the double walled tubing is placed in-line with production tubing.
 17. The method of claim 15, wherein the double walled tubing is placed around production tubing in the form of a segmented jacket.
 18. The method of claim 15, wherein the double walled tube comprises a baffle.
 19. The method of claim 18, wherein the baffle comprises transfer holes.
 20. The method of claim 15, wherein the heating element provides heat to the production tube, warming material flowing through the production tube. 